/*
 * @Date: 2021-09-10 07:59:48
 * @Author: Acckno1
 * @LastEditTime: 2021-09-10 08:21:24
 * @Description: 
 */
#include <iostream>
#include <cstring>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <set>
#include <bitset>
#include <utility>
using namespace std;

#define mm(a, n) memset(a, n, sizeof a)
#define mk(a, b) make_pair(a, b)

const double eps = 1e-6;
const int INF = 0x3f3f3f3f;

typedef long long LL;
typedef unsigned long long ULL;
typedef pair<int, int> PII;
typedef pair<double, double> PDD;
typedef pair<LL, LL> PLL;
typedef pair<int, LL> PIL;

inline void quickread() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
}

const int N = 2e4 + 10;

int MSize, n, m;
int nums[N];

bool is_prime(int n) {
    for (int i = 2; i * 2 <= n; i ++ ) 
        if (n % i == 0) return false;
    return true; 
}

inline void solution() {
    cin >> MSize >> n >> m;
    mm(nums, -1);
    while (!is_prime(MSize)) MSize ++ ;
    for (int i = 0; i < n; i ++ ) {
        int v;
        cin >> v;
        bool inserted = false;
        for (int j = 0; j <= MSize; j ++ ) {
            int pos = (v + j * j) % MSize;
            if (nums[pos] == -1) {
                nums[pos] = v;
                inserted = true;
                break;
            }
        }
        if (!inserted) cout << v << " cannot be inserted." << endl;
    }
    int ans = 0;
    for (int i = 0; i < m; i ++ ) {
        int v;
        cin >> v;
        for (int j = 0; j <= MSize; j ++ ) {
            int pos = (v + j * j) % MSize;
            ans ++ ;
            if (nums[pos] == v || nums[pos] == -1) break;
        }
    }
    printf("%.1lf\n", ans * 1.0 / m);
}

int main() {
    freopen("input.txt", "r", stdin);
    quickread();
    solution();
    return 0;
}